Monarchs and Milkweed: A Migrating Butterfly, a Poisonous Plant, and Their Remarkable Story of Coevolution

Known for their bright colors and epic annual migration from the United States and Canada to Mexico, monarch butterflies are beautiful but complicated creatures of nature. Anurag Agrawal presents a detailed investigation into how the monarch butterfly’s relationship has evolved to coexist with the incredibly toxic milkweed in his new book Monarchs and Milkweed (Princeton University Press; April 11, 2017).

The inextricable and intimate relationship between the monarch butterfly and the milkweed plant has been like an arms race over the millennia. Each spring, the monarch life cycle begins when it deposits eggs on the leaves. Even though the plants do all they can to poison the predators, the larvae appear to feed exclusively on them. The milky sap poisons contained in leaves and stems have not only shaped monarch-milkweed interactions but have been culturally important for centuries. In a Chats in the Stacks book talk hosted by Mann Library, Agrawal will discuss his recent scientific discoveries that reveal a battle of exploitation and defense between these two fascinating species. He will also review current ideas regarding the recent decline in monarch populations, the influence of habitat destruction, and his own theories as to why their numbers are plummeting.

Anurag Agrawal is professor of ecology and evolutionary biology in the College of Agriculture and Life Sciences at Cornell University.